OP0227 WEIGHT LOSS IS ASSOCIATED WITH REDUCED INCIDENCE AND PROGRESSION OF STRUCTURAL DEFECTS IN KNEE OSTEOARTHRITIS, AS ASSESSED BY RADIOGRAPHY OVER 4 TO 5 YEARS: A PROSPECTIVE MULTI-COHORT STUDY
Authors: Z. Salis, H. Keen, B. Gallego, T. V. Nguyen, A. Sainsbury-Salis
Journal: Annals of the Rheumatic Diseases (2022)

Background Overweight and obesity are associated with greater incidence and progression of the structural defects of knee osteoarthritis, but it is unknown if weight loss is of benefit. Objectives To describe the association between change in body mass index (BMI) and the incidence and progression of structural defects in knee osteoarthritis. Methods Scores from radiographic analyses of knees at baseline and at 4 to 5 years’ follow up were obtained from three independent data sets (the OAI and MOST data sets from the United States from America, and the CHECK data set from the Netherlands). The exposure of interest was change in BMI from baseline to 4 to 5 years’ follow up. To investigate the incidence of structural defects of knee osteoarthritis, we selected a total of 9732 knees (from 5802 participants) that had a Kellgren-Lawrence (KL) grade of knee osteoarthritis at baseline of ‘none’ (0) or ‘doubtful’ (1) (the ‘incidence cohort’), and determined the odds of having a KL grade at follow-up of ‘minimal’ (2), ‘moderate’ (3), or ‘severe’ (4). To investigate progression, we selected a total of 6084 knees (from 3996 participants) that had a KL grade at baseline of ‘minimal’ (2), ‘moderate’ (3), or ‘severe’ (4) (the ‘progression cohort’), and determined the odds of increasing by 1 or more KL grades by follow up. The degradation of three individual structural features of knee osteoarthritis (i.e., joint space narrowing, osteophytes on the femoral surface, and osteophytes on the tibial surface), on both the medial and lateral sides of the knee, were also investigated in both the incidence and progression cohorts. Here, degradation was defined as an increase by 1 or more Osteoarthritis Research Society International (OARSI) grades. Results Change in BMI was positively associated with both the incidence and progression of knee osteoarthritis, as defined by KL grade. Specifically, for each one-unit change in BMI, the adjusted odds ratio for incidence was 1.05 (95% confidence interval [CI] 1.02 to 1.09), and for progression, the same adjusted odds ratio and 95% CI was also observed. Change in BMI was also positively associated with degradation (i.e., narrowing) of joint space on the medial but not the lateral side of the knee, with an adjusted odds ratio of 1.08 (95% CI 1.04 to 1.12) in the ‘incidence cohort’ and 1.08 (95% CI 1.03 to 1.12) in the ‘progression cohort’. Degradation of the tibial and femoral surfaces (i.e., osteophytes) was also seen on the medial but not the lateral side of the knee, but only in one of the two cohorts investigated (the ‘incidence cohort’), with an adjusted odds ratio of 1.07 (95% CI 1.03 to 1.12) for osteophytes on the femoral surface, and 1.05 (95% CI 1.01 to 1.09) for osteophytes on the tibial surface. Conclusion Each one-unit reduction in BMI is associated with a 5 to 8% decrease in the odds of the incidence and progression of the structural defects of knee osteoarthritis, with lower odds of structural degradation specific to the medial – not lateral – side of the knee. Acknowledgements We acknowledge the provision of datasets and/or research tools from three studies: the Osteoarthritis Initiative (OAI) Study; the Multicenter Osteoarthritis Study (MOST); and the Cohort Hip and Cohort Knee (CHECK) Study. OAI is a collaborative informatics system created by the National Institute of Mental Health and the National Institute of Arthritis, Musculoskeletal and Skin Diseases (NIAMS) to provide a worldwide resource to quicken the pace of biomarker identification, scientific investigation and OA drug development. The OAI data repository is housed within the National Institute of Mental Health (NIMH) Data Archive (NDA). For the MOST data set, we wish to acknowledge the contributions of the study participants, investigators and research staff involved. MOST is comprised of four (4) cooperative grants: U01 AG18820 David T. Felson (Boston University); U01 AG18832 James Torner (University of Iowa); U01 AG18947 Cora E. Lewis (University of Alabama at Birmingham); U01 AG19069 Michael C. Nevitt (University of California, San Francisco), funded by the National Institutes of Health, a branch of the Department of Health and Human Services, and conducted by MOST investigators. This manuscript was prepared using MOST data and does not claim, infer, or imply endorsement by MOST, by the MOST investigators and their respective institutions or by the University of California of the Data Recipients’ use of the Data, of the entity or personnel conducting the research, or of any results of the research. The CHECK study is funded by the Dutch Arthritis Foundation. Involved are: Erasmus Medical Center Rotterdam; Kennemer Gasthuis Haarlem; Leiden University Medical Center; Maastricht University Medical Center; Martini Hospital Groningen /Allied Health Care Center for Rheumatology and Rehabilitation Groningen; Medical Spectrum Twente Enschede /Ziekenhuisgroep Twente Almelo; Reade Center for Rehabilitation and Rheumatology; St.Maartens-kliniek Nijmegen; University Medical Center Utrecht and Wilhelmina Hospital Assen. Disclosure of Interests Zubeyir Salis: None declared, Helen Keen: None declared, Blanca Gallego: None declared, Tuan van Nguyen: None declared, Amanda Sainsbury Speakers bureau: ZS and AS own 50% each of the shares in Zuman International, which receives royalties for books AS has written and payments for presentations, and provides paid training for higher degree students. AS additionally reports receiving presentation fees and travel reimbursements from Eli Lilly and Co, the Pharmacy Guild of Australia, Novo Nordisk, the Dietitians Association of Australia, Shoalhaven Family Medical Centres, the Pharmaceutical Society of Australia, and Metagenics, and serving on the Nestlé Health Science Optifast VLCD advisory board from 2016 to 2018., Consultant of: ZS and AS own 50% each of the shares in Zuman International, which receives royalties for books AS has written and payments for presentations, and provides paid training for higher degree students. AS additionally reports receiving presentation fees and travel reimbursements from Eli Lilly and Co, the Pharmacy Guild of Australia, Novo Nordisk, the Dietitians Association of Australia, Shoalhaven Family Medical Centres, the Pharmaceutical Society of Australia, and Metagenics, and serving on the Nestlé Health Science Optifast VLCD advisory board from 2016 to 2018.